Economics, not national security, was the main topic Saturday as Democratic presidential hopefuls Bernie Sanders and Martin O’Malley tried to tie front-runner Hillary Rodham Clinton to Wall Street and big money donors in a nationally televised debate from Des Moines, Iowa.

For the Vermont senator and former Maryland governor, it was an all-out appeal to the progressive wing of the Democratic Party, which has long held concerns about the centrist leanings of both Clinton and her husband, former President Bill Clinton.

“Let’s not be naive about it,” Sanders said when asked whether Clinton’s support from Wall Street could compromise her ability to be president. “Why, over her political career, has Wall Street been ... the major campaign contributor to Hillary Clinton? ... Why do they make millions of dollars of campaign contributions? They expect to get something. Everyone knows that.”

O’Malley piled on, saying that the economy has been wrecked “by the big banks of Wall Street” and that Clinton’s proposal to rein in the nation’s leading financial institutions was “weak tea.”

“I won’t be taking my orders from Wall Street,” he said. “We expect that our president will protect the Main Street economy from excesses on Wall Street.”

Clinton, who as senator from New York — home of Wall Street — argued that she would be tough on banks and other financial institutions and that “if the big banks don’t play by the rules, I will break them up.”

That brought another explosion from Sanders, who time after time Saturday stressed the need to break up the biggest banks.

“Wall Street played by the rules?” he asked. “Who are we kidding? The business model of Wall Street is fraud.”

For Sanders, it was not an evening to play down his history as a self-proclaimed socialist — he called for a revolution to change the way the country is run. Instead, he went all in on his plans for free college education, a single-payer health-care system, a $15 national minimum wage and boosting taxes on the wealthy.

“Every issue I am talking about ... is supported by a significant majority of the American people,” Sanders said. “What the political revolution is about is bringing people together to finally say, ‘Enough it enough.’ This government belongs to us, not just the billionaires.”

For O’Malley, with only single-digit support in most recent polls, the debate was a chance — maybe his last chance — to grab enough support to challenge Clinton. He pounded on his time as mayor of Baltimore and as Maryland governor, arguing that gave him the governing experience the other two candidates lack.

O’Malley talked about how he raised the state sales tax to improve Maryland’s education system and boosted taxes on the richest residents as part of his blueprint for improving the state.

“While other candidates will talk about the things they would like to do, I actually got things done,” he said.

While the debate was mostly polite, O’Mally, 52, took a thinly disguised slap at both Clinton, 68, and Sanders, 74, with a call for new leadership and an end to “polarizing figures” of the past.

But for Clinton, the debate was more about not making mistakes and looking forward to a vision she believes is shared by the mainstream Democrats and independents who will be voting in the upcoming primaries.

She reminded viewers that as secretary of state she was one of the advisers who told President Obama he should send in the team to take out Osama bin Laden, that 60 percent of the donors to her campaign are women and that she has reason to know just how far to the left Americans are willing to go.

Asked about her earlier support for a form of single-payer health insurance when her husband was president, she admitted that didn’t work out so well.

“The revolution never came, and I have the scars to prove it,” she said.

The problem for all three Democrats is that while they differ on specifics, they have few disagreements on basic plans and principles.

On subjects like immigration, criminal justice and national security, the disputes were around the edges, not on the important parts of policy.